In the last few years, scientists have been performing spectroscopic analysis of matter using high energy pulses from a laser. An effort is made to study changes in materials which occur during extremely short periods of time, in the pico and sub-picosecond range.
As research has progressed, a desire for higher power lasers has developed. The availability of higher power lasers permits investigation of higher order, nonlinear effects in materials subjected to the laser excitation. A wide variety of wavelengths of laser light is also desired to expand the range of spectral analysis. As will be discussed below, lasers designed to produce a higher output power and greater spectral range have more constraints which give rise to certain operational difficulties. In the past, the suppression of the second pulse in a cavity could be easily handled. However, the solutions available in the past have not proved feasible with the higher powered systems.